On Tue, Sep 10 2019, Guoqing Jiang wrote: > On 9/10/19 5:45 PM, Song Liu wrote: >> >> >>> On Sep 10, 2019, at 12:33 AM, NeilBrown wrote: >>> >>> On Mon, Sep 09 2019, Song Liu wrote: >>> >>>> Hi Neil, >>>> >>>>> On Sep 9, 2019, at 7:57 AM, NeilBrown wrote: >>>>> >>>>> >>>>> If the drives in a RAID0 are not all the same size, the array is >>>>> divided into zones. >>>>> The first zone covers all drives, to the size of the smallest. >>>>> The second zone covers all drives larger than the smallest, up to >>>>> the size of the second smallest - etc. >>>>> >>>>> A change in Linux 3.14 unintentionally changed the layout for the >>>>> second and subsequent zones. All the correct data is still stored, but >>>>> each chunk may be assigned to a different device than in pre-3.14 kernels. >>>>> This can lead to data corruption. >>>>> >>>>> It is not possible to determine what layout to use - it depends which >>>>> kernel the data was written by. >>>>> So we add a module parameter to allow the old (0) or new (1) layout to be >>>>> specified, and refused to assemble an affected array if that parameter is >>>>> not set. >>>>> >>>>> Fixes: 20d0189b1012 ("block: Introduce new bio_split()") >>>>> cc: stable@vger.kernel.org (3.14+) >>>>> Signed-off-by: NeilBrown >>>> >>>> Thanks for the patches. They look great. However, I am having problem >>>> apply them (not sure whether it is a problem on my side). Could you >>>> please push it somewhere so I can use cherry-pick instead? >>> >>> I rebased them on block/for-next, fixed the problems that Guoqing found, >>> and pushed them to >>> https://github.com/neilbrown/linux md/raid0 >>> >>> NeilBrown >> >> Thanks Neil! > > Thanks for the explanation about set the flag. > >> >> Guoqing, if this looks good, please reply with your Reviewed-by >> or Acked-by. > > No more comments from my side, but I am not sure if it is better/possible to use one > sysfs node to control the behavior instead of module parameter, then we can support > different raid0 layout dynamically. A strength of module parameters is that you can set them in /etc/modprobe.d/00-local.conf and then they are automatically set on boot. For sysfs, you need some tool to set them. > > Anyway, Acked-by: Guoqing Jiang > Thanks, NeilBrown > Thanks, > Guoqing